Tick
struct Slot0 {
// 当前价格 平方根
uint160 sqrtPriceX96;
// tick 索引
int24 tick;
// the most-recently updated index of the observations array
uint16 observationIndex;
// the current maximum number of observations that are being stored
uint16 observationCardinality;
// the next maximum number of observations to store, triggered in observations.write
uint16 observationCardinalityNext;
// the current protocol fee as a percentage of the swap fee taken on withdrawal
// represented as an integer denominator (1/x)%
uint8 feeProtocol;
// whether the pool is locked
bool unlocked;
}